Abstract
The corrosion attack inside the wet section of the automotive exhaust systems is caused by acidic condensates and chlorides. The corrosion resistance of the different stainless steels in the wet corrosion loading was usually achieved in a lot different test procedures. A new test method has been developed and leads to a new test specification which is recommended by the German Association of the Automotive Industry (VDA). This test specification affords a basis for the investigation of the corrosion behavior of stainless steels for automotive exhaust systems. The test method considers the wet-dry-alternation, the impact of the chloride ions in an acidic medium and the temperature stress inside the system. The influence of the soot particles is missing in this test standard. Furthermore in addition to the new test method electrochemically active carbon was added inside the system. By adding active carbon the impact of the soot particles on the corrosion attack is simulated. The results of the tests show that active carbon has a significant influence on the corrosion attack. This circumstance should be considered in future test methods for stainless steels used in the automotive exhaust systems.
Keywords: stainless steels, pitting corrosion, soot particles, test method